1. Field of the Invention
The present invention relates to a control circuit for reducing touch current of a power converter and an operation method thereof, and particularly to a control circuit and an operation method thereof that can reduce touch current generated by a quick decrease voltage of an input capacitor of a power converter when the power converter leaves a burst mode.
2. Description of the Prior Art
In the prior art, when a power converter with power factor correction (PFC) is in operation of a high output voltage and alight load, the power converter can enters a burst mode. After the power converter enters the burst mode, a power switch of the power converter can be switched according to a gate control signal corresponding to the burst mode. Meanwhile, because power consumption of the power converter is very small, an input capacitor of the power converter can be maintained at a voltage when the power switch stops being switched. When the power converter leaves the burst mode, the power switch starts to be switched according to the gate control signal corresponding to a quasi resonant mode. Meanwhile, if an input voltage is less than the voltage of the input capacitor, diodes of a bridge rectifier of the power converter would be turned off, resulting in the input capacitor providing power to an inductor of the power converter. Thus, the voltage of the input capacitor is decreased. Meanwhile, the voltage of the input capacitor is quickly decreased because the power converter is operated on the highest frequency thereof, resulting in a touch current of the power converter exceeds a safety specification.
In addition, the prior art can only adjust parameters of the power converter to solve a problem of larger touch current, so the prior art can only solve the problem of larger touch current partially. Therefore, a designer of the power converter needs to find a new solution to substitute for the prior art.